金属表面非相干线结构光条纹中心提取方法

采用线结构光法测量金属表面形貌时，由于受到金属表面光学特性和散斑噪声的影响，条纹中心的提取误差往往较大。为此，提出了一种非相干线结构光形貌测量方法，避免了散斑噪声的影响。通过分析该方法测量金属表面形貌时的条纹图像特点，提出一种适合非相干线结构光条纹的中心提取方法。该方法首先采用结合积分图像原理的自适应阈值分割算法，对原条纹图像进行分割。采用灰度重心法粗提取原条纹中心坐标，以该坐标为基准向条纹宽度方向延伸，从而确定阈值分割后条纹图的感兴趣区和背景区，并去除背景区的噪声。经中值滤波后，采用几何中心法提取条纹中心。实验结果表明:采用该方法提取粗糙度样块表面非相干光条纹中心的平均误差为1.5 μm，提取齿轮渐开线样板表面非相干光条纹中心的平均误差为0.9 μm，均比其线激光条纹中心的提取误差小。所提方法能实现金属表面非相干线结构光条纹中心的精确提取。

Extraction of incoherent linear structured light stripe center on metal surface

When the metal surface profile is measured by the linear structured light method, the extraction error of stripe center is often large due to the influence of optical properties and speckle noise of metal surface. Therefore, a profile measurement method that used incoherent linear structured light was proposed, which could avoid the influence of speckle noise. A corresponding method for extracting the center of incoherent linear structured light stripe was proposed by analyzing the characteristics of metal surface profile stripe images. Firstly, the original stripe image was segmented using adaptive threshold segmentation algorithm combined with integral image principle. Then, the center coordinates of original stripe were roughly extracted by gray centroid method. The regions of interest and background of stripe image after threshold segmentation were determined by extending the roughly center to stripe width direction, and the noise in the background region was removed. Finally, the stripe center was extracted by geometric center method after median filtering. The experimental results show that the average error of incoherent light stripe center of roughness specimen surface extracted by proposed method was 1.5 μm and that of involute gear was 0.9 μm, which are both smaller than those of line laser stripes. The proposed method can accurately extract the center of incoherent linear structured light stripe on metal surface.